1. Field of the Invention
The present invention is generally related to a marine propulsion shift procedure and, more particularly, to a method for providing a shift interrupt system that requires little or no actual rotation of shift assembly components in order to provide a signal that a shift operation is beginning.
2. Description of the Prior Art
In various types of equipment powered by internal combustion engines, it is beneficial to sense the initiation of a gear shift operation and take steps to interrupt the operation of the engine during the shifting procedure. The shift interrupt process reduces the effort necessary to accomplish the gear shift operation by momentarily reducing the forces on the gear shift apparatus. One application where a shift interrupt procedures is used is in conjunction with a marine propulsion system.
U.S. Pat. No. 5,470,264, which issued to Eick on Nov. 28, 1995, discloses a marine drive shift shaft mounting system. A device is provided for isolating a shift shaft extending through an exhaust passage of a bell housing in a marine drive system. The device includes an elongated sleeve for receiving the shift shaft therein. The sleeve has a first portion sealably mounted in a first bore extending through the top wall of the exhaust passage and a second portion sealably mounted in a second bore which extends through the bottom wall of the exhaust passage. The elongated sleeve prevents galvanic corrosion and erosion of the aluminum housing and the stainless steel shaft.
U.S. Pat. No. 6,544,083, which issued to Sawyer et al. on Apr. 8, 2003, discloses a shift mechanism for a marine propulsion system. A gear shift mechanism is provided in which a cam structure comprises a protrusion which is shaped to extend into a channel formed in a cam follower structure. The cam follower structure can be provided with first and second channels that allow the protrusion of the cam to be extended into either channel which accommodates both port and starboard shifting mechanisms. The cam surface formed on the protrusion of the cam moves in contact with a selected cam follower surface formed in the selected one of two alternative channels to cause the cam follower to move axially and to cause a clutch member to engage with either a first or second drive gear.
U.S. Pat. No. 5,052,958, which issued to Entringer et al. on Oct. 1, 1991, discloses a marine drive with easier shifting. The drive has a driveshaft housing including a bell housing with an exhaust passage therethrough directing exhaust gas and cooling water, and a shift shaft extending through the exhaust passage and journaled in the bell housing by a bushing in a bore in a section of the bell housing. The interface of the bushing and the bore is subject to corrosion from exhaust gas and cooling water. Shifting is eased by enabling a portion of the bushing to contract radially inwardly toward the shift shaft due to the noted corrosion, without binding the shift shaft and otherwise impeding rotation thereof.
U.S. Pat. No. 6,102,830, which issued to Tsutsui et al. on Aug. 15, 2000, describes a shift control device for an automatic transmission. When a shift to a second gear ratio is determined during a shift control for a first shift, the process status, or circumstances, of the first shift is determined using a hydraulic pressure for a fourth brake being engaged at the determination. When the process status, that is, the process circumstances, is in an early phase, the first shift is interrupted and shift control for the direct shift to the second ratio is performed. When the process status is in a late phase, the first shift control is continued, and after ending of the first shift control, the control for the shift to the second gear ratio is performed. In the case of power off state, the second shift pattern is performed irrespective of the process status.
U.S. Pat. No. 4,753,618, which issued to Entringer on Jun. 28, 1988, discloses a shift cable assembly for a marine drive. A shift cable assembly for a marine drive includes a shift plate, a shift lever pivotally mounted on the plate, and a switch actuating arm pivotally mounted on the plate between a first neutral position and a second switch actuating position. A control cable and drive cable interconnect the shift lever and switching actuating arm with a remote control and clutch and gear assembly for the marine drive so that shifting of the remote control by a boat operator moves the cables to pivot the shift lever and switch actuating arm which in turn actuates a shift interrupter switch mounted on the plate to momentarily interrupt ignition of the drive unit to permit easier shifting into forward, neutral and reverse gears. A spring biases the arm into its neutral position is and the arm includes an improved mounting for retaining the spring in its proper location on the arm.
U.S. Pat. No. 4,432,734, which issued to Bland et al. on Feb. 21, 1984, describes a marine propulsion device including ignition interruption means to assist transmission shifting. Shifting a marine propulsion device transmission drivingly connecting a drive shaft to an internal combustion engine and including a rotatable member operable to shift the transmission between forward drive, reverse drive and neutral positions in response to rotation of a shift lever is assisted by an arrangement including a pin or element pivotally connected to a push-pull assembly operated by a main control and carried by the shift lever. The shift assistance arrangement includes a spring which retains the element in a normal position relative to the shift lever when shift resistance to movement of the transmission from an “in gear” to the neutral position is less than a predetermined level and permits displacement of the element relative to the shift lever from the normal position when the shift resistance is above that predetermined level. The shift assistance arrangement also includes a switch operable when actuated to selectively interrupt engine ignition. This switch is carried on the shift lever and is s actuated to interrupt engine ignition in response to displacement of the element from the normal position.
U.S. Pat. No. 4,262,622 which issued to Dretzka et al. on Apr. 21, 1981, describes a marine propulsion device including ignition interruption means to assist transmission shifting. The marine propulsion device includes an internal combustion engine and a reversing transmission having a pair of bevel gears and a clutch dog movable between a neutral position out of engagement with the bevel gears and forward and reverse drive positions in full engagement with one of the bevel gears. The marine propulsion device also includes a shift assistance arrangement included in a shift mechanism for axially moving the clutch dog between the neutral and drive positions, and which includes a load sensing lost motion shift lever arrangement having a first switch which is actuated when the resistance to axially moving the clutch dog into a drive position exceeds an upper limit.
U.S. Pat. No. 5,700,168, which issued to Mondek et al. on Dec. 23, 1997, describes an electronic ignition interruption apparatus. A shift interrupt apparatus for a marine drive of the type which has an ignition system and a transmission that is adapted to be selectively shifted among forward, neutral and reverse operating positions is described. A control member is provided for selectively positioning the transmission of the drive into forward, neutral and reverse operating positions. The apparatus has a light circuit associated with the mechanical assembly adapted to detect excessive shifting force, which generates an electrical signal for interrupting the ignition to facilitate easier shifting.
U.S. Pat. No. 5,708,216, which issued to Garshelis on Jan. 13, 1998, describes a circularly magnetized non-contact torque sensor and method for measuring torque using the sensor. A torque sensor for providing an output signal indicative of the torque applied to a rotating torqued member comprises a magnetoelastically active element for producing a magnetic field varying with the applied torque and a field modulating means for modulating the magnetic field in a periodic manner which is indicative of the speed of member rotation. A magnetic field vector sensor, such as a Hall effect sensor, senses the amplitude of the modulated field for providing an output signal which is linearly indicative of the lo torque applied to the rotating member.
U.S. Pat. No. 6,490,934, which issued to Garshelis on Dec. 10, 2002, describes a circularly magnetized non-contact torque sensor and method for measuring torque using the sensor. The sensor is indicated for providing an output signal indicative of the torque applied to a member and includes a ferromagnetic, magnetostrictive, magnetoelastically active region on or in the member, the region being proportionally subjected to the torque applied to the member. The region is endowed with an effective uniaxial magnetic anisotropy having the circumferential direction as the easy axis and is magnetically polarized in a single circumferential direction. When torque is applied to the member, the magnetoelastically active region produces a magnetic field varying with the torque, which field is sensed by magnetic field sensors arranged proximate the region.
U.S. Pat. No. 6,301,976, which issued to Bogdanov on Oct. 16, 2001, describes a torque sensing apparatus having a magnetoelastic member secured to a shaft. A shaft experiences torsion about its axis in response to an applied torque. A cylindrical magnetoelastic member is secured coaxially about the shaft. The magnetoelastic member has first and second spaced apart end portions. Each end portion is chamfered at a predetermined angle with respect to a plane extending perpendicular to the shaft axis. The magnetoelastic member provides a magnetic field in response to the torsion of the shaft. A detector is positioned adjacent to the magnetoelastic member for sensing the magnetic field and providing a signal indicative of the applied torque.
U.S. Pat. No. 5,692,992, which issued to Arvidsson et al. on Dec. 2, 1997, describes a shift assist and engine interrupter apparatus. The apparatus includes a tube having a pair of biased springs, between which a sleeve at the end of a transmission cable is movably retained. A remote control cable is fixedly attached to the tube. High transmission cable shift forces associated with resistance to shifting caused the sleeve to move against the bias of one of the springs. A sensor detects this movement and sends an electrical signal to interrupt the engine ignition circuit, thereby preventing the firing of one or more cylinders of the engine. The interruption of the engine ignition reduces the torque on the shift mechanism, in turn reducing the shift forces in the transmission cable and enabling the operator to shift the transmission. When the shift operation is completed, the engine resumes normal firing.
U.S. Pat. No. 4,762,008, which issued to Kobayashi et al. on Aug. 9, 1988, describes a torque detecting apparatus. The apparatus utilizes a magnetoelastic effect comprising one or more pairs of thin magnetic metal strips affixed to a torque-transmitting shaft subjected to torque detection and having a magnetic anisotropy induced in a predetermined direction, and one or more pairs of detecting cores paired with the above one or more pairs of thin magnetic metal strips, fixed in contact with the thin magnetic metal strips, each of the cores of the one or more pairs of detecting cores having a detecting coil wound therearound. In one embodiment, the torque detecting apparatus utilizes a magnetoelastic effect of thin magnetic metal strip wherein the absolute value of saturated magnetostriction constant of the thin magnetic metal strip is less than 1×10−6.
U.S. Pat. No. 6,467,360, which issued to Bogdanov on Oct. 22, 2002, describes a torque sensing apparatus and method. The torque sensing apparatus is used for sensing torque applied to an elongated shaft having a longitudinal axis. An elongated magnetoelastic element is connected about a portion of the shaft. The magnetoelastic element provides a magnetic field in response to a torque applied to the shaft. The magnetic member is positioned adjacent the magnetoelastic element. An alternating power source drives the magnetic member into magnetic saturation. The magnetic member has a saturation condition responsive to the magnetic field of the magnetoelastic element. A detector circuit detects the saturation condition of the magnetic member. The detector circuit provides a signal indicative of the applied torque in response to the saturation condition of the magnetic member.
U.S. Pat. No. 6,598,491, which issued to Opie et al. on Jul. 29, 2003, describes a magnetoelastic torque sensor. The sensor is intended for measuring the magnitude of torque applied to a member, comprising a magnetoelastic element which is disposed on and encircles the member, an outer flux guide extending across the magnetoelastic element in an axial direction and adjacent to the opposite end regions thereof, and an inner flux guide located between the first and second end regions, wherein the inner and outer flux guides provide a magnetic path to an axial component of the magnetic field produced by the magnetoelastic element in response to a non-zero value of torque.
The patents described above are hereby expressly incorporated by reference in the description of the present invention.
A pamphlet titled “The New Standard for Torque Sensing” is provided by the Magnetoelastic Devices Corporation. It describes the technology relating to magnetoelastic sensing, compares this technology to other types of torque sensors, and discusses its principals of operation. In addition to describing the theory behind magnetoelastic sensing, this pamphlet also provides examples of how magnetoelastic sensing can be applied in various industries.
In a shift interruption system, one inherent problem is that sensing the initiation of the shifting procedure requires that the shifting apparatus actually move from a resting position. In known sensing systems, this is necessary because physical movement of the shifting apparatus is necessary in order to actuate a switch or sensor that is used to determine the onset of a shifting procedure so that the internal combustion engine associated with the apparatus can be interrupted. Because of the necessity of this actual movement of the shifting apparatus, a certain amount of lost motion occurs before the shifting process can be sensed and any interrupting process can begin. This, in turn, limits the timeliness of the interruption procedure. It would therefore be significantly beneficial if a method could be determined which allows the shift interruption procedure to begin more quickly upon the initial onset of the shifting process by the operator of a vehicle, such as a marine vessel. In other words, it would be beneficial if the onset of the shift procedure could be sensed immediately when the operator of the vehicle begins to move a shift lever from its resting position to a new position.